In U.S. Pat. No. 4,727,135 there is described a method for polymerizing certain aromatic nitrogen-containing heterocyclic compounds using a metal sulfide catalyst in which the metal is selected from the group consisting of transition metals of Group VIB, VIIB and VIII of the Periodic Table or mixtures thereof. The preferred catalyst for the polymerization of the aromatic, nitrogen-containing heterocyclic compounds is reported to be rhenium sulfide, ReS.sub.2+X.
In Catalyst Letters, 1, 177 to 182 (1988), two soluble rhenium complexes are reported to be useful in generating rhenium sulfides that are catalytically active in the dehydrogenative polymerization of 1,2,3,4-tetrahydroquinoline.
We now have discovered a new series of organic amine-containing metal sulfide compounds that are particularly suitable as catalysts for the dehydrogenative polymerization of aromatic, nitrogencontaining heterocyclic compounds like tetrahydroquinoline.